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arj_y2k
10th June 2002, 08:55 PM
G'Day,
I have a Clarion VNET 450 (4 x 50WRMS) amp. I had it running my Kenwood fronts and a JL sub when a couple of months ago, the front left speaker dropped out. After checking all the wiring and the speaker, I took it to Supertech Electronics (Bundall, Gold Coast) who said the 6 "fets" in the amp needed to be replaced. This was going to cost me $140 so I bought a new amp instead. My question is, what are these fets, and what do they do? Are they easy to replace (solder out, solder in) and what are they worth? Where can I get them from and are any of you guys able to do the repair or know of anyone who can (for a reasonable price that is)? Any help appreciated.
Andrew
BootySlap
11th June 2002, 02:42 PM
a 'fet' is a field effective transistor. Usually they are called Mosfet's or JFets.

In Metal-Oxide semiconductor field effect transistor the MOS bit is the method of fabrication of the transistor and the FET bit essentially means a transistor which uses an electric field to control the current.

Try http://www.jaycar.com.au or http://www.dse.com.au they sell a few Mosfets but finding the right one to replace your supposed dead ones might be difficult!
arj_y2k
11th June 2002, 10:20 PM
Thanks for the info. Is there a way to tell which ones are stuffed? Can you run a multimeter across them to see if they're working or is it a bit harder than that? Also, what do they look like and where on the circuit board can they usually be found? Im guessing that if the guy said he'd have to replace 6 fets to fix the one channel, then there would be a total or 24 fets in the amps. Does this sound right or was he just trying to get more money out of me?
Cheers.
AJ
BootySlap
12th June 2002, 10:10 AM
Well have a look at this http://www.utm.edu/~leeb/mostest.htm
But i dont think all mosfets in an amp are normal transistors like those and some might be surface mount so it will be a hard time testing them.

Im presuming he says you will have to replace the mosfets is because he has experienced and seen amps die before and that is normally the thing that is wrong with them?

Anyway im no qualified elec. engineer !!